Snap switch



Patented June 17, 1952 SNAP swl'rcH Leo J. Kmiecik, Chicago, Ill.,assigner to Mc- Donnell & Miller, Inc., Chicago, Ill., a corporation ofDelaware Application April 11, 1949, Serial No. 86,773

This invention relates to a snap device such as a snap switch or thelike and more particularly concerns improvements in a snap switch orlike structure of the kind covered in Leo J. Kmiecik Patent No.2,454,185 issued November` 16, 1948.

In a snap device such as a snap switch of the type covered in myaforesaid issued patent quick responsiveness and high speed operationare highly important practical factors. Simplicity and ease ofmanufacture, sturdiness and reliability in operation are also important.

It is, accordingly, an important object of the present invention toprovide an improved, simple and compact snap device which particularlylends itself to use as a snap switch and includes a novel assembly ofoperating parts for rapid response and high speed operation with minimumoperational deflection of actuating means for the device.

Another object of thev invention is to provide in a snap device whereina pair of angular members are cooperatively disposed for relativerocking movement in operation, improvements in the mounting of suchmembers to increase the speed of operative reaction of the members.

A further object of the invention is to provide in a snap switch or likesnap device improvements in various operating parts embodyingsimplications and increasing the efficiency thereof.

Still another object of the invention is to provide an improved snapdevice of increased operating sensitivity.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of a preferredembodiment thereof taken in conjunction with the accompanying drawingswherein:

Figure 1 is a horizontal sectional View through the illustratedembodiment of the invention, taken substantially on the line I-I ofFigure 2;

Figure 2 is a vertical sectional view through the illustrated snapswitch embodiment taken substantially on the line Ill-l1 of Figure 1;

Figure 3 is a vertical sectional view substantially like Figure 2 butshowing the mechanism in a different operative relationship; and

Figure 4 is an isometric view of the overcenter interconnecting memberoperative between the short legs of the relatively rockable levermembers of the assembly.

As shown on the drawings:

A snap device embodying the features of the present invention isespecially useful in a snap switch assembly adapted to be housed in atwo- 1 Claim. (Cl. 200-67) part casing which may comprise a base IU anda hollow cover II. In an e-flicient form the casing may be made from anysuitable dielectrical material such, for example, as a phenoliccondensation product, or the like.

The cover II provides therein a chamber I 3 housing the severaloperating components of the snap assembly including relatively rockablelever members I4 and I5 and an actuating lever member I1. All of thelever members are preferably of generally L-shape. The lever member I4has a long leg I 2 including an intermediate portion I8 and a short legI9. The lever member I5 has a long leg 20 and a short leg 2|. The levermember I 1 has a long leg 22 and a short leg 23. The construction andrelationship of the lever members is suchthat swinging of the levermember I1 effects rocking of the lever member I5 and, in turn, relativeopposite rocking of the lever member I4.

All of the levers I4, I5 and I1 are preferably mounted upon a commonmounting. member 24 which may be formed as a sheet metal stamping havinga base 25 which is secured to the casing base l0 by means such as anelectrical contact terminal body member 21 forming part of a contactterminal assembly 28. The body member 21 is preferably tubular andsecured within an aperture 28a in the casing base I0, with an attachmentflange 29 turned over into retaining engagement with the, supportingmember base 25 and a retaining terminal flange 30 at its outer endsecured against the outer sideA of the casing base I 0 about theaperture 28. The contact body member 21 is internally threaded and has aterminal screw 3l threaded thereinto and retaining a contact cup washer`33.

For supporting the rockable arms I4 and I5 pivotally, the supportingmember 25 has a pair of spaced parallel upstanding arms or ears 34between which respective pairs of depending ears 35 and 31 onrespectively the arm I4 and the arm I5 are received. Pivotal bearing forthe ears 35 and 31 is provided by respective pintle pins 38 and 39.Thereby the pivots for the respective rockable levers I4'and I5 areoffset from one another, with the pivot for the arm I4 offset in thedirection of they short leg I9 of such arm from the pivot for therocking lever I5. It may also be noted that the pivot ears 31 of therocking lever I5 are longer than the pivo't ears 35 of the rocking leverI4 whereby the lever I5 is supported in superposed spaced relation withrespect to its long leg 20 above the long leg I8 of the rocking leverI4. The short leg I9 of the rocking lever I4 is spaced from the shortleg 2| of the rocking lever 20 so that a substantial range of relativerocking of the substantially internested levers I4 and I5 is permitted.

Means are provided to act between the short legs I9 and 2| of therocking lever members I4 and I5 to function responsive to movement ofone of the levers to carry its shorter leg selectively to either side ofan aligned position of the short legs of the levers. To this end, theshort leg 2| of the rocking lever I5 is longer than the short leg I9 ofthe rocking lever I4 so that in relative opposite rocking of the leversthe end portions of the short legs will move to respective oppositesides of an aligned condition Vof the end portions of the short legsunder the inuence of an over center connecting member 4D. In a preferredform the over center member 40 comprises a substantially at plate havingthe opposite ends thereof notched out as at 4I and 42 and with which areengaged respectively the end portions of the short legs I9 and 2 I, theshort leg I9 being provided for this purpose with channeled terminalportion 43 while the leg 2| is provided with a channeled portion 44. Thechanneled terminal portions 43 and 44 open toward each other and engagethe respective ends of the over center member 40 within the notches 4|and 42, respectively. The length of the member 40 between the engagedportions of the short legs I 9 and 2| is slightly greater than thenormal spacing between the legs in the aligned condition of the legs sothat a condition of stress is generated whenever the short legs I9 and2| come into alignment, and the over center member 40 therefore acts tomove over center by pivoting at its end edges in the channeled terminalportions 43 and 44 of the short legs.

In order to provide for resilient yielding of the cooperating structuresto relieve the stress imposed by action of the over center member 40 inthe aligned position of the short legs I9 and 2|, the over center member40 may be formed as a resilient spring to absorb all of the stress, orit may be formed as a rigid plate, but it is preferably slightlyyieldable or sprngy, and the major proportion of the resilient yieldingoccurs in one of the short lever legs, in the present instance the shortleg 2| of the rocking lever I5. To this end, the short leg 2| is formedfrom resilient relatively thin stock, preferably separately from thebody of the rocking lever I5 and has an angular connecting flangeportion 45 which is secured to the long leg as by means of a rivet 41.Thus, when either of the levers I4 or I5 is rocked the over centermember 40 acts to snap the remaining lever rockingly in the oppositedirection upon movement of the short legs I9 and 2| beyond center ineither direction.

In the present instance, the rockinglever I5 is arranged to be actuatedby the actuating lever I1 to effect opposite rocking of the rockinglever I4 as a function of the over center member 40 coacting with therocking levers. For this purpose, an end portion of the actuating leverI1 is interconnected with the free end portion of the rocking lever I5by extending through a slotted angular flange 48 at the free terminus ofthe lever I5. At its opposite end, the actuating lever I1 has the shortleg 23 thereof fixedly secured to an upstanding angular supporting leg49 integral with the base of the supporting member 24.

By preference the actuating lever I1 is in the form of a leaf springwhich, by reason of its fixed attachment to the supporting leg 49 no1'-mally assumes a biased position adjacent to the roof of the chamber I3where it is engaged by an operating plunger 50 reciprocably slidablycarried in a hollow boss 5| on the cover I I. The outer end of theplunger 50 projects outwardly beyond the outer end of the boss 5I and isthus adapted to be pressed inwardly to ex the actuating spring lever |1so as to rock the rock lever I5 and cause the over center piece 40 tosnap the rock lever I4 in the opposite rocking direction. Release ofpressure on the operating plunger 50 allows the spring lever I1 toreturn of its own l resilience to its normally biased position to rockthe lever I5 in reverse and thus cause the lever I4 to be snapped backto initial position.

In order to improve the action of the actuating spring lever I1, astiffening brace or reinforcement is provided for the short leg 23thereof and the adjacent portion of the long leg 22. Efficient means forthis purpose comprises an angular sheet metal member 52 seated withinthe reentrant corner of the spring lever member and having a leg securedas by means of a rivet 53 to the lon-g leg 22. The remaining leg of thebrace member 52 has a hollow tapped boss 54 into which a screw 55 isthreaded to attach the assembly to the supporting leg 49, the short leg23 of the spring lever being clamped by the contiguous tapped boss legof the member 52 to the supporting leg 49. This not only results in arelatively simple and economical structure but affords a stifening forthe attached end portion of the spring lever I1 so as to increase theresilient bias thereof to normal position.

In addition, the rock lever engaging end portion of the actuating springlever I1 is preferably substantially stiffened by reinforcing ribembossment thereof, a longitudinal reinforcing rib 51 being formed inthe extremity portion which is engaged with the connecting flange 48 ofthe engaged rock lever. Inwardly from the free end of the spring leverleg 22, the reinforcing rib 51 is forked to provide parallel sidemarginal ribs 58 defining therebetween a plunger seat area 59. The sideribs 58 terminate just beyond the point where the plunger 50 engages theseating area 59 and the portion of the spring lever leg 22 between theends of the reinforcing ribs 58 and the adjacent leg of the reinforcingand bracing member 52 is relatively freely flexible. Inasmuch as theamount of flexing required in the leg 22 is very limited the freeflexing area of the spring lever leg is ample for the purposes of thesnap device and is free from any over stressing such as might causefatigue failure. Due to the relative stiffness of all other portions ofthe actuating lever, the lever has a very quick action.

In its rocking movements, the rocking lever I4 functions to make andbreak an Ielectrical circuit one branch of which is connected to theconnector member 30 and another branch of which is connected to aconnector stud 60 by means of a screw 6I threaded into an outwardlyopening bore `|52 lcoaxially in the stud, .the head of the screw beingreceived within a terminal cup 63 similar to the terminal cup 33. Thestud 60 is secured in the casing base I0 under the long leg I8 of themake and break lever in appropriately spaced relation to the contactmember 21, extending through an appropriate aperture in the casing basewith a shoulder 64 engaging against the inner face of the casing baseand a retaining flange 65 upset against the outer face of the easingbase to retain the stud xedly in position. At its inner end the stud Siihas a `contact head El provided with a deterioration resistant contacttip 68 which is preferably formed with a depending stem `E59press-fitted into an axial aperture or socket 'i8 in the contact head,

Electrical contact between the make and break lever i4 and the contacttip 8B is effected by means of `a contact button 'H lmounted on ailexible leaf carrier 'l2 of substantial length and secured as by meansof a rivet 'i3 to the long lever leg I8 adjacent to the pivoted portionthereof while the opposite end of the leaf is formed with an upwardly`and return lbent fiexure limit flange 'Ill cooperating with the end ofthe long leg I8 within a notch 75. AThe terminal button is convenientlyconnected with the carrying leaf 72 by means of a stem 71 which, afterassembly is spread into interlocking relation at the opposite side ofthe leaf 'i2 from the head of the button and about the rim of anappropriate aperture in the leaf. A -clearance aperture 'i3 for the stem'il is provided in the long leg I8 of the make and break lever. Thepurpose of mounting the contact button 'I'I on the flexible carryingleaf 'I2 is to limit the separation distance when the contacts areseparated and also to delay the contact break upon movement of the leverI4 until the lever has accelerated in its contact breaking rockingmovement sufficiently to separate the contact button 1I from thelcontact head 88 at high speed. Engagement of the turned over terminalof the terminal flange 75 with the upper side of the long lever leg I8limits the ilexure separation of the carrying leaf 'I2 from the adjacentface of the lever leg I8.

Limit upon the distance to which the make and break lever Ill may swingto contact-breaking position is accomplished by the provision of a stopshoulder 'I9 formed integral with the casing closure cap Il and opposingthe free end portion of the long lever leg I8. By having the turned overterminal of the interengagement flange 'I4 of the contact carrying leafengageable with the shoulder 'i9 relieves the shoulder from tendency tobe gouged out by the ends of the lever leg I8 at each side of the notch'I5 and permits the lever I4 to be made more economically than if thefree end terminal portions thereof were specially formed to present flatcontact areas to the shoulder 19.

Strain upon the intermediate rocking lever I5 by action of the overcenter member 49 in the contact making or closed circuit condition ofthe snap device is accomplished by the provision of a pair of mov-ementlimiting angular legs 88 on the outer end of the over center member 48which, in the closed circuit condition of the assembly engage as stopsagainst the retaining member base -as seen in Figure 2.

From the foregoing it will be apparent that the present inventionprovides a snap device of unusually compact form and rapid action.Normally the three cooperating levers are in the closed circuitcondition of the assembly as seen in Figure 2, being thus maintained bythe normal bias of the actuating spring cantilever I7 which drawsupwardly on the free end of the intermediate lever I5 and thus maintainsthe short leg 2l thereof in its downward position so that the overcenter member 4) acts on the short leg I9 of the make and break lever I4to hold the same in its upward position and thus the long leg I8 in itsdownward position wherein the contacts `E58 and 'II are in engagement.Upon only slight depression of the operating plunger il@ to effectdownward flexing of the long leg 22 of the actuating cantilever and thusdownward swinging of the long leg 2l) of the intermediate lever l5 andupward rocking of the Short leg 2l movement of the short leg 2l past thealigned position of the short legs 2l and I9 occurs and the over centermember i9 snaps the make and break lever I ll in reverse rockingmovement to snap the switch open, to the position shown in Fig. 3.

Exceptionally short movement to effect this result at high speed resultsfrom the offset relationship of the rocking lever pivotsl wherein thepivot 38 of the make `and break lever I4 is l0- cated at an increaseddistance from the contact 83 as compared to the pivot 39 for theintermediate lever l5 with the result that the fulcrum of the lever I isas close as practicable to its actuated end, thus rendering the shortend of the lever as short as practicable and the long end of the leveras long as practicable so that a small rocking movement of the short endof the lever effects a correspondingly long rocking motion of the longend of the lever. These highly desirable results are reflectedthroughout the mechanism since the flexing distance of the actuatingspring lever I'I is correspondingly reduced and the rocking range of theintermediate lever I5 is correspondingly reduced. This is advantageousin numerous respects among which may be mentioned minimizing strain uponthe flexed portion of the actuating lever I'I and thus permitting suchspring lever to be conditioned for improved high speed responsiveresilience. The limitation upon necessary movement of the variousbearing parts reduces wear and thus increases the life of the unit. Theoverall improved high speed responsiveness of the unit increase thespeed of apparatus with which the snap switch unit is used as a controldevice.

I claim as my invention:

In a snap switch or like device, a first member pivoted on an axisadjacent one end thereof, a movable switch contact carried by said rstmember adjacent the other end thereof, a stationary switch contactengageable with said rst switch contact, a second member insubstantially spaced superposed relationship to said first member inopen and closed positions of said switch, said second member beingpivoted about an axis laterally spaced from and intermediate the pivotalaxis of said iirst member and said switch contacts, over-center springmeans between said one end of said first member andthe adjacent end ofsaid second member, and actuating means engageable with said secondmember adjacent the other end thereof to displace said overcenter springmeansI with respect to said adjacent ends of said members to effectactuation of said switch.

LEO J. KMIECIK.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,538,938 Hulse May 26, 19252,170,748 Eaton Aug. 22, 1939 2,232,243 Judson Feb. 18, 1941 2,318,734Baak May 11, 1943 2,454,185 Kmiecik NOV. 16, 1948 2,487,374 Riche Nov.8, 1949

